WorksheetsUnit 6 Changes in Reactants and Products
Total questions: 23
Worksheet time: 12mins
Name
Class
Date
1.
Which of the following is an example of a chemical reaction?
a)
Water evaporating from a pot on a hot stove
b)
Sand being removed from sea water by filtration
c)
A spoonful of sugar dissolving in a glass of water
d)
A white solid forming when two clear liquids are poured together
2.
Which of the following always results from a chemical reaction?
a)
Fire
b)
Bubbles
c)
A new substance that is a solid
d)
A new substance that can be a solid, liquid, or gas
3.
Which of the following is an example of a chemical reaction?
a)
A marshmallow turning black when heated over a fire
b)
A powder dissolving in water to make lemonade
c)
An ice cube melting into a puddle of water
d)
Salt crystals being crushed into a powder
4.
Which of the following is an example of a physical change?
a)
The surface of a copper penny changing color after being in a drawer for years
b)
Melted butter becoming a solid when placed in the refrigerator
c)
A car rusting when exposed to the air and rain
d)
Bread toasting
5.
Chemistry is
a)
a characteristic of a substance that can be observed without changing the substance into another substance.
b)
the study of matter and how matter changes.
c)
anything that has mass and takes up space.
d)
a rapid reaction between oxygen and a substance called a fuel.
6.
Which of the following is NOT a correct inference that you can make about the burning of gasoline?
a)
Chemical bonds are broken and others are formed.
b)
The reaction is a physical change.
c)
New substances are produced.
d)
Energy is released.
7.
What happens when chemical bonds break and new bonds form?
a)
a physical change
b)
a chemical reaction
c)
matter is destroyed
d)
surface area increases
8.
CaCO3 represents a chemical
a)
Symbol
b)
Formula
c)
Subscript
d)
Reaction
9.
The only sure evidence for a chemical reaction is
a)
the formation of a gas.
b)
a color change.
c)
the production of one or more new substances.
d)
changes in properties.
10.
The substances listed on the left side of a chemical equation are the
a)
Products
b)
Coefficients
c)
Precipitates
d)
Reactants
11.
In chemical reactions, what does the principle of conservation of mass mean?
a)
Matter is not created or destroyed.
b)
The total mass of the reactants is greater than the total mass of the products.
c)
The total mass of the reactants is less than the total mass of the products.
d)
Matter is not changed.
12.
A chemical reaction that absorbs energy in the form of heat is described as
a)
endothermic
b)
exothermic
c)
combustion
d)
unbalanced
13.
The principle of conservation of mass is true
a)
only for reactions that take place in open systems.
b)
only for reactions that take place in closed systems.
c)
for reactions in both open and closed systems.
d)
for no reactions at all.
14.
Which of the following is NOT a physical property?
a)
flexibility
b)
flamability
c)
melting point
d)
ability to conduct electricity
15.
A change in state (ie. melting, boiling, etc.) is always what type of change?
a)
Physical Change
b)
Chemical Change
c)
Precipitate Change
d)
Exothermic Change
16.
A solid that forms from solution during a chemical reaction is a(n)
a)
precipitate
b)
reactant
c)
product
d)
byproduct
17.
A physical change can best be demonstrated by
a)
burning an index card
b)
leaving the index card unchanged
c)
cutting the index card in half
d)
bleaching the index card
18.
When heated, oxygen reacts with copper to form copper oxide:
If this reaction occurs in a sealed container, will the mass of the container and everything in it increase, decrease, or stay the same and why?
If this reaction occurs in a sealed container, will the mass of the container and everything in it increase, decrease, or stay the same and why?
a)
The mass will stay the same because the number of each kind of atom stays the same.
b)
The mass will increase because a new kind of molecule is formed.
c)
The mass will decrease because two substances combine to form one substance.
d)
More information is needed to tell if the mass will change.
19.
What type of reaction is occurring in the diagram? Which response below explains the reason for that type of reaction?
a)
Exothermic. Heat is released when the candle (wax) burns.
b)
Endothermic. Heat is released when the candle (wax) burns.
c)
Exothermic. Heat is taken in when the candle (wax) burns.
d)
Endothermic. Heat is taken in when the candle (wax) burns.
20.
When the candle was lit, a pool of liquid wax formed in the area around the wick, and then spilled over the side and resolidified. Does this observation refer to a physical change or a chemical change? Explain.
a)
A chemical change. The substance was still wax, but it changed to a liquid and then back to a solid.
b)
A physical change. The substance was still wax, but it changed to a liquid and then back to a solid.
c)
A chemical change. The substance changed from a chemical liquid to solid wax.
d)
A physical change. The substance was still wax, but it changed to a solid and then back to a liquid.
21.
The flame from the candle gives off black smoke. Does this statement describe evidence for a physical change or a chemical change? Explain.
a)
A chemical change. The black smoke is evidence that a new substance is not forming which means a chemical change occurred.
b)
A physical change. The black smoke is evidence of the formation of a new substance, which means a chemical change occurred.
c)
A chemical change. The black smoke is evidence of the formation of a new substance, which means a chemical change occurred.
d)
A physical change. The black smoke is evidence of a solid turning into a gas
22.
Identify the reactant(s) and product(s) of the reaction.
a)
All three are reactants and none are products.
b)
Hydrogen and water are the reactants, and oxygen is the product.
c)
Water and oxygen are the reactants, and hydrogen is the product.
d)
Hydrogen and oxygen are the reactants, and water is the product.
23.
A student determines the density, solubility, and boiling point of two liquids, Liquid 1 and Liquid 2. Then he stirs the two liquids together and heats them. After stirring and heating the liquids, two different liquids form, Liquid 3 and Liquid 4. Then the student determines the density, solubility, and boiling point of Liquids 3 and 4. He concludes that a chemical reaction occurred. Here are his results:
How does the student know a chemical reaction has occurred?
How does the student know a chemical reaction has occurred?
a)
The student knows that a physical reaction has occurred because Liquids 1 and 2 have different physical properties.
b)
The student knows that a chemical reaction has not occurred because Liquids 3 and 4 have different properties than Liquids 1 and 2.
c)
The student knows that a chemical reaction has occurred because Liquids 3 and 4 have different properties than Liquids 1 and 2.
d)
The student knows that a physical reaction has occurred because Liquids 3 and 4 have different properties than Liquids 1 and 2.
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